Wow, the difference a quality rotor makes!

[irie]

Have a Trek Fuel EX 5 which is bottom of the 2021 range and which I knew I'd have to customise to get it the way I wanted. Have converted to tubeless and tuned the cockpit but a couple of times I've found the Shimano MT200 brakes and Shimano RT56 rotors (180mm) 'underwhelming' (aka brown trousering) on a downhill.

So instead of mucking around upgrading the brake sets I got a pair of Shimano RT86 Ice-Tech rotors (180mm) with new B01S pads and carefully broke them in. Fuck me, the improvement in braking is staggering! My rear is a bit spongy compared to the front but I think that's because the rear hose is (obviously) longer than the front and can be sorted by using Shimano BH90 hose (5mm, 2.1mmm bore) instead of the current Shimano BH69 hose (5mm, 2.3mm).

No change to m/c's or calipers. Result.

[weeksy]

that surprises me without changing the pads.... or even the rotor size etc...

It could be though that the new rotors are fractionally wider, so you now have less free play before the bite.

It's quite a common trick with some brakes to remove the wheel, pump the lever once and then refit, that brings it all a bit closer and gives a firm lever. It does though leave you slightly open to getting rubbish/squeak.

[irie]

Both rotors are identical thickness (1.8mm) when measured with the same Moore and Wright calipers, but they are neither identical construction nor materials.

The bloke in a local independent shop (a retired downhill racer) that I've known for over 10 years said that from his experience the RT86 rotors really do work a lot better than cheaper rotors such as RT56. So I took him at his word and bought the rotors on the internet, and he's so far proved to be right. Will have to watch longer term performance, of course

[irie]

Have now gilded the lilly and put Shimano M6100 twin pot brakes on. Talk about stopping power!

[Taff]

I've just changed my disks from a 180mm to 203mm, it took quite a while for the pads & rotors to properly bed in - read that as, they scared the shit out of me on the first ride because they barely worked meaning that I was going far faster down hill than I was happy with...

the difference now is not in the outright braking power as it was never really lacking with the 180's, but the amount of effort I put into the lever for the same braking performance is quite a bit less.

[Mussels]

Have a Trek Fuel EX 5 which is bottom of the 2021 range and which I knew I'd have to customise to get it the way I wanted. Have converted to tubeless and tuned the cockpit but a couple of times I've found the Shimano MT200 brakes and Shimano RT56 rotors (180mm) 'underwhelming' (aka brown trousering) on a downhill.

So instead of mucking around upgrading the brake sets I got a pair of Shimano RT86 Ice-Tech rotors (180mm) with new B01S pads and carefully broke them in. Fuck me, the improvement in braking is staggering! My rear is a bit spongy compared to the front but I think that's because the rear hose is (obviously) longer than the front and can be sorted by using Shimano BH90 hose (5mm, 2.1mmm bore) instead of the current Shimano BH69 hose (5mm, 2.3mm).

No change to m/c's or calipers. Result.

Are they the same pads you had before?

[irie]

Have a Trek Fuel EX 5 which is bottom of the 2021 range and which I knew I'd have to customise to get it the way I wanted. Have converted to tubeless and tuned the cockpit but a couple of times I've found the Shimano MT200 brakes and Shimano RT56 rotors (180mm) 'underwhelming' (aka brown trousering) on a downhill.

So instead of mucking around upgrading the brake sets I got a pair of Shimano RT86 Ice-Tech rotors (180mm) with new B01S pads and carefully broke them in. Fuck me, the improvement in braking is staggering! My rear is a bit spongy compared to the front but I think that's because the rear hose is (obviously) longer than the front and can be sorted by using Shimano BH90 hose (5mm, 2.1mmm bore) instead of the current Shimano BH69 hose (5mm, 2.3mm).

No change to m/c's or calipers. Result.

Are they the same pads you had before?

Same part number but a new set (the old pads were only about 10% into maximum wear level, but not glazed btw).

[irie]

Well, I went full Monty and replaced the Shimano MT200's with M6100 brakes. So much better modulation, and the stopping power is just Glad I didn't get the M6120 4 pots tbh ...